Supercharger control means for internal combustion engine

Abstract

A supercharged internal combustion engine comprising a combustion chamber of which volume cyclically changes in response to a rotation of the engine to conduct engine operating strokes including an intake and compression strokes, an intake system for supplying intake gas to the combustion chamber. The intake system includes a main intake passage having one end connected with the combustion chamber to have the intake gas therein taken into the combustion chamber under a suction pressure prevailing in the combustion chamber, a main throttle valve provided in the main intake passage, an auxiliary intake passage having one end connected with the combustion chamber, a supercharger provided in the auxiliary intake passage for providing a supply of supercharging gas to the combustion chamber, an auxiliary throttle valve provided in the auxiliary intake passage downstream of the supercharger, a timing valve provided in the auxiliary intake passage downstream of the auxiliary throttle valve, a valve operating device for operating the timing valve in response to the rotation of the engine, an engine load sensor for detecting engine load, a valve timing control device for controlling opening timing of the timing valve so that the timing valve is opened at least in a beginning period of the compression stroke, the valve timing control device is so designed that the opening timing is advanced in response to a decrease in the engine load.

We claim: 
     
       1. A supercharged internal combustion engine comprising working chamber means of which volume cyclically changes in response to a rotation of the engine to conduct engine operating strokes including an intake and compression strokes, an intake system for supplying intake gas to said working chamber means, said intake system including main intake passage means having one end connected with said working chamber means to have the intake gas therein taken into the working chamber means under a suction pressure prevailing in the working chamber means, main throttle valve means provided in said main intake passage means, auxiliary intake passage means having one end connected with the working chamber means, supercharging means provided in said auxiliary intake passage means for providing a supply of supercharging gas to said working chamber means, auxiliary throttle valve means provided in said auxiliary intake passage means downstream of said supercharging means, timing valve means provided in said auxiliary intake passage means downstream of said auxiliary throttle valve means, valve operating means for operating said timing valve means in response to the rotation of the engine, engine load sensing means for detecting engine load, valve timing control means for controlling opening timing of the timing valve means so that the timing valve means is opened at least in a beginning period of the compression stroke, said valve timing control means including means for controlling the opening timing so that the opening timing is advanced in response to a decrease in the engine load. 
     
     
       2. An engine in accordance with claim 1 in which said timing valve means comprises a rotary valve element disposed in said auxiliary intake passage means and having first opening means for passing the intake gas therethrough, and a sleeve fitted to said rotary valve element rotatably with respect to the rotary valve element and having second opening means for cooperation with said first opening means in the rotary valve element, said valve timing control means including means for determining rotational position of the sleeve. 
     
     
       3. An engine in accordance with claim 2 in which said valve timing control means includes a servomotor for rotating the sleeve and control circuit means for controlling the servomotor. 
     
     
       4. An engine in accordance with claim 2 in which said valve timing control means includes a suction pressure operated actuator for rotating the sleeve under a suction pressure in the main intake passage means downstream of said main throttle valve means. 
     
     
       5. An engine in accordance with claim 1 in which said engine load sensing means is means detecting position of said main throttle valve means, and the last mentioned means in said valve timing control means is means for controlling the opening timing in reverse proportion to the engine load. 
     
     
       6. An engine in accordance with claim 1 in which said valve timing control means further includes means for controlling the opening timing in accordance with engine speed so that the opening timing is advanced in response to an increase in the engine speed.